Operating mechanism



July 1, 1941. c. THUMIM OPERATING MECHANISM Filed April 3, 1940 2Sheets-Sheet 1 Fig. l.

Inventor: Car"! Thumlm,

1 Z Hus Attorney July 1, 1941. c. THUMIMI 2,247,862

OPERATING MECHANISM I Filed April 5, 1940 fSheets-Sheet 2 Inventor:

C r! Thumirn y n27 M His 'trtomey.

Patented July 1, 1941 OPERATING MECHANISM Carl Thumim, Yeadon, Pa.,assignor to General Electric Company, a corporation of New YorkApplication April 3, 1940, Serial No. 327,624

6 Claims.

My invention relates to operating mechanisms for electric circuitbreakers of the reclosing type and more particularly to operatingmechanisms which are so constructed and arranged that very high-speedreclosing of the circuit breaker is possible.

It has been found that perhaps 75 or 80 per cent of the abnormal currentconditions or faults which initiate operation of protective apparatus,such as circuit breakers, are temporary and, furthermore, of very shortduration. For example, abnormal current surges in transmission lines dueto lightning often die out within a few microseconds. It would bedesirable in order to maintain good continuity of service for theprotective apparatus to distinguish between such temporary or transientfaults and prevent the circuit breakers from tripping under suchconditions. The above problem may be substantially solved by high-speedreclosing circuit breakers which reclose within a very short interval oftime so that the synchronism of the system is not disturbed.

One of the factors which limits the minimum time necessary for thereclosing of circuit breakers is the time required for resetting thetripping linkage which holds the circuit breaker in the closed position.In the prior art arrangements, the entire linkage is reset at once sothat, in order to decrease the resetting time, arrangements have beenproposed wherein large accelerating forces have been provided in theshape of springs or the like. In such arrangements, the resetting timeis decreased at the expense of sensitivity of the protective systemsince the heavier springs require stronger tripping forces. Inaccordance with my invention, rapid reclosing of the circuit breaker ismade possible by preresetting as many of the heavy parts of the trippinglinkage immediately after the tripping action is initiated and duringthe opening stroke of the circuit breaker so as to leave only a latch ofnegligible mass finally to be reset when the circuit breaker isreclosed, whereby excessively large springs can be avoided and yetresetting time reduced.

It is an object of my invention, therefore, to provide a new andimproved operating mechanism for a very high speed reclosing circuitbreaker which is simple and economical in construction to the extentthat a minimum of mov ing parts are involved and which is eflicient andreliable in operation.

It is another object of my invention to provide a new and improvedoperating mechanism for electric circuit breakers in which the resettinglinkage which is slow to reset is reset during the breaker openingstroke so as to be in readiness for immediate reclosing of the circuitbreaker.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming .a part of this specification.

For a better understanding of my invention, reference may be had to theaccompanying drawings in which Fig. 1 is an elevational view partly insection of a circuit breaker operating mechanism embodying my invention,Fig. 2 is an enlarged perspective View of a portion of the apparatusillustrated in Fig. 1, Fig. 3 represents an operating mechanismembodying a modification of my invention, while Figs. 4 and 5 aremodifications of the arrangement illustrated in Fig. 3.

Referring more particularly to Fig. 1, the operating mechanism showntherein comprises an actuating means or solenoid ID for actuating areciprocally guided rod II which, for example, may be connected tooperate a suitable circuit breaker, not shown. A collapsibleforce-transmitting structure l2 interconnects actuating means It andactuated means or red H. The collapsible force-transmitting structure [2per se forms no part of the present invention and is illustrated as ofthe character disclosed and claimed in my United States Letters PatentNo. 2,112,054 granted March 22, 1938, and assigned to the same assigneeas the present invention.

Although a description of the collapsible forcetransmitting structure [2is available in the above-mentioned patent, a brief description thereofwill be included hereinafter. Solenoid I0 is provided with an armatureit which is connected to rod H by a chain linkage l4 normally guided ona grooved roller 55 carried by a bell crank 16 pivotally mounted at IT.When the bell crank I6 is held in the position shown by means of alatching mechanism generally indicated at [8 and described in greaterdetail hereinafter, energization of solenoid it causes downward movementof armature l3 and closing movement of the circuit breaker, not shown,associated with rod ll against the bias of energystorage means I9, therelease of which causes high-speed opening of the associated circuitbreaker. In order that energy-storage: means 19 may remain charged aftersolenoid H! is deenergized, I provide a suitable prop 221 spring biasedat 2| which cooperates with pin 22 so that armature i3 is held in itslower position. By this arrangement, the circuit breaier may be held inthe closed position by the cooperative action of the prop 2B andlatching means it, the latter cooperating with roller as oeiated withcrank i5. It will be understood that solenoid H3 is provided with asm'table control circuit to energize it for automatic reclosing trippingof the circuit breaker.

With the apparatus in the position indicated in Fig. l, the release oilatching means restraining roller 23 and hence oell cran would allow theenergy stored in the spring to due to the force on grooved roller 55acting through the moment indicated at a, cause a clockwise rotation ofth bell crank it to the position shown in dott d lines in l. Acomparatively sensitive tripping device for latching means Hi can beused if desired since the required tripping force is directly related tothe length of the moment arm indicated at a through which the resultantreacting force at the chain linkage tends to produce clockwise rotationof bell crank iii. Where the lever arm a is quite small, thelatch-releasing force required is obviously small.

in order that resetting of the collapsible forcetransmitting structure92 may occur as soon as the tripping action of the circuit breaker isinitiated, bell crank it"; is provided with a portion [6 which serves asa cam member for engaging the extension 24 suitably welded to prop 2:3.Hence, after a predetermined rotation of hell crank i8, the member isengaged and prop Z is moved to free pin 22, whereby the energy in spring25 is released to cause an upward movement of armature l3 of solenoidIii. This affords additional slack in chain linkage it so that bellcrank Hi can immediately reset to the position shown in solid lines inFig. 1 and, due to the energy stored in spring 26 when bell crank 16 isrotated in the clockwise direction. The above-described arrangement issubstantially identical with the apparatus described and claimed in myabovementioned United States Letters Patent.

In order to save time in the resetting of latching means it, with whichmy invention is particularly concerned, I provide an arrangement wher inthe parts which are slow to reset do so immediately after the trippingaction and during the opening stroke of the circuit breaker so that onlya relatively light part must be finely reset when the breaker isreclosed. Latching means I8 shown in an enlarged perspective view inFig. 2 includes a collapsible member including pawl 2"! of negligiblemass and to a limited extent relatively movable with respect to theremaining portions of latching means i8 which comprise shaft 28 providedwith an offset arm or extension 29 rigidly fastened thereto as bysuitable fastening means 38. Oifset arm 29 is adapted to engage or coactwith the plun er 3! of the conventional tripping solenoid 32. A suitablestop 3-3 is provided for limiting the downward movement of offset arm 29and a relatively light spring-biasing means 85 may be provided ifdesired for resetting shaft 23 and oifset arm 29 when tripping solenoid32 is no longe energized.

Since shaft 28 and extension 23 are relatively heavy, they haveconsiderable inertia and re quire a relatively long time within which toreset after a trip-ping movement thereof especially in view of the factthat spring means 34 should be relatively weak so that a very smalltripping force from plunger 3! may cause tripping of the circuitbreaker. In order to form the collapsible member of latching means I 8,pawl 21 is mounted for limited rotation on shaft 28 by being providedwith an enlarged segmental keyway 35 cooperating with a key 355 suitablyfitted into shaft 28. The segmental keyway 35 is of such a size as toallow sufficient relative rotation between pawl 21 and shaft 28 when theresetting of bell crank l5 occurs so that the relatively heavy portions28 and 29 of the collapsible member of latching means is need not bedisturbed after having been reset. A relatively heavy spring 37 isprovided to cause pawl 2'! to return to restrain roller 23 immediatelyafter bell crank l6 has been reset.

Manual tripping of the latching means I8 is suitably provided by meansof a lever 33 indepondently pivotally mounted on shaft 28 and co actingwith a pin 33 carried by the extension 29. A manually operable link 4i!is connected to the lever 38 for rotating the latching means 18clockwise in the manner above described.

The operation of the apparatus illustrated in Fig. l and moreparticularly the operation of the latching means l3 best shown in Fig. 2will be apparent to those skilled in the art and, therefore, will onlybe briefly described. It is obvious that actuation of the trip-pingsolenoid 32 due to some abnormal current condition will cause elevationof tripping plunger 3! and clockwise rotation of extension 29 andrigidly attached shaft 23 which latter may be suitably mounted in thehousing which surrounds the operating mechanism. Such clockwise rotationof shaft 28 will cause similar clockwise rotation of pawl 2'! formingthe remaining portion of the collapsible member of latching means l8since key 36 is engaged with one edge of segmental keyway 35. Suchrotation of pawl 21 releases roller 23 whereby bell crank i6 is nolonger restrained and the energy stored in spring means 19 is releasedto cause opening movement of the circuit breaker, not shown. As soon astripping solenoid 32 is deenergized, the collapsible member comprisingpawl 27, shaft 28, and extension 28 begins to reset under the relativelysmall force of spring 34. This resetting may be accomplished immediatelyafter the tripping impulse and dining the opening stroke of the circuitbreaker. In order to reclose the circuit breaker, it is merely necessaryfor pawl 21 of negligible mass to move against the force of its spring31 relative to shaft 28 so that roller 23 of bell crank l5 may again berestrained by latching means i8. Therefore, high-speed reclosing of thecircuit breaker is possible since the relatively heavy and slow parts oflatching means l8 are reset early and the final member to be reset issufliciently small and biased by relatively heavy springs to resetalmost instantly after reclosing of the circuit breaker. Furthermore, inthe arrangement just described, the relatively heavy spring 31 has noeffect in so far as decreasing the sensitivity of the tripping apparatusis concerned.

In certain a'rangements, the tripping force available is so small as tobe unsatisfactory for tripping an arrangement even like that describedabove which requires a relatively small tripping force. In sucharrangements, it is necessary to include energy-storage means which maybe released. by a very sensitive tripping force and which, in turn,supply a larger tripping force such as is necessary for tripping acircuit breaker. Because of the additional tripping element required, myinvention is particularly applicable to such arrangements wherein thesensitive tripping means which requires a great deal of time to resetmay be reset immediately so that the apparatus is ready for high-speedautomatic reolosing. In the arrangements to be described hereinafter,therefore, the sensitive latch is permitted to start resettingimmediately after being tripped even though the associated circuitbreaker has completed only a small part of its opening stroke.

In Fig. 3, I have illustrated my invention as embodied in an operatingmechanism of the impact trip type with electric spring reset means. Theoperating mechanism comprises an actuating means or solenoid ll and anactuated means comprising rod 442 which may be operatively connected toa suitable circuit breaker or to any other apparatus to which thisoperating mechanismmay be applied. A collapsible force-transmittingstructure 53 interconnects actuating means ll and actuated means or rod42. The collapsible force-transmitting structure per se forms no part ofthe present invention and is illustrated as of the character disclosedand claimed in my United States Letters Patent No. 1,988,287, grantedJanuary 15, 1935, and assigned to the same assignee as the presentinvention.

Although a description of the collapsible force-transmitting structureis available in the above-mentioned patent, a brief description hereofwill be included hereinafter. Collapsible force-transmitting struture 13is trip free in operation, that is, the rod 32 may be released at anytime during or after the closing stroke of solenoid E and comprises amember or link at, one end of which is pivoted at iii while its otherend provided with a roller d6 coacts with pivoted latch member ll. LinkAid restrained by latch member ll forms a mounting for a floating link48 pivotally carried at 49 by link it and operatively connected. as at50 to the rod 32. The floating member is arranged to be rotated aboutthe restraining pivot by means of plunger 5! of solenoid 4i whichengages with a roller 52 suitably mounted at the other end of floatingmember All, thereby causing positive movement of rod 42 in the downwarddirection to close the associated circuit breaker. In Fig. 3, rod 42 isshown in its lowermost position which represents the closed position ofthe associated circuit breaker. In order that rod 42 may be restrainedin this lowermost position after solenoid 41 is deenergized, a suitableprop 53 is provided pivotally mounted at 54 and normally biased as by aspring 55 in a clockwise direction so that the supporting edge of prep53 rides under and supports the roller pin 5?. Further movement of propin the clockwise direction is limited by a stop portion 58 which engagesa suitable fixed frame or housing member.

In view of the fact that in large circuit breakers the reacting forcebetween roller "it and latching member e? is relatively large, a feebletripping force would be insufficient to release roller all from therestraining action of latch ll. For the purpose of efliciently operatingthe abovedescribed mechanism when but feeble tripping impulses areavailable, there is provided an auxiliary tripping unit for providingthe force nece sary to release roller $6 from the restraining action oflatch 47. This auxiliary tripping unit comprises a bell crank 5tpivotally mounted at (ill and having one end thereof connected to a rod5| through a suitable auxiliary source of tripping energy which, in thiscase, is illustrated as a spring means E52 arranged to be charged bymeans of solenoid 63 having its armature G4 Fig. 3

connected with rod 6|. Solenoid 63* is arranged to be energized from asuitable source of energy 65 through overcenter type switch 66 wheneverthe energy stored in spring 62 is released to trip latch 41. This isaccomplished by connecting over center type switch 66 to armature 64 ofsolenoid 63 so that, whenever the energy stored in spring 62 isreleased, overcenter type switch 66 is closed to energize solenoid 63and recharge spring 62 for the next succeeding tripping action. Whenspring 62 is released, the rapid upward movement of rod 6| causescounterclockwise rotation of bell crank 59 which is provided with asuitable pin 61 to engage as by impact latch 47' which is held in theposition shown in Fig. 1 by means of stop 68. Latch 4? is provided withsuitable spring means 69 which may be relatively heavy to cause rapidresetting thereof, in view of the relatively large amount of impact tripenergy available from spring means 62.

Bell crank 59 and spring 62 are restrained in the position shown in Fig.3 by means of a collapsible latching member '10 including a pawl H whichengages with a roller 72 at one end of bell crank 59. Collapsible member1B is pivotally mounted at l3 and biased against stop member 54 byspring means 75. Pawl H, which is of negligible mass relative to theremaining portion of collapsible latching means 50, is pivotally mountedto the latter at 18 and biased to the position shown in Fig. 3 wherestop member ll of pawl Ti engages with the edge of the relatively heavyportion of collapsible latching means H! by virtue of the bias of springmeans 18. Spring means 69 and 18 may be relatively heavy to decrease theresetting time of pawl II and latch ll. Collapsible latching means it)by being pivotally mounted at 13 provides a considerable force reductionat the end thereof supporting roller ill as compared to the force actingat the other end thereof against pawl ll.

Collapsible latching means 19 is restrained in the position shown inFig. 3 by means of sensitive latch 30 biased to the position shownagainst stop ill by a very light spring 82 so that it may be tripped bya feeble thrust from sensitive solenoid 33, which is arranged to engagean extension 84 of sensitive latch 80.

The operation of the apparatus illustrated in and more particularly theoperation of the latching means will be only briefly describedhereinafter. Sensitive latch is rotated in a counterclockwise directionin response to a feeble tripping force from solenoid 33 because of therelatively small mass of sensitive latch 89 and also because spring 82is very weak. Such counterclockwise movement releases collapsiblelatching means 10 which also rotates in a counterclockwise direction sothat roller i2 is no longer restrained and crank 59 is free to rotateunder the force of spring 82 which is now released causing pin ill tostrike latch 41 rotating it in a counterclockwise direction so that thecollapsible force-transmitting structure 43 will allow the circuitbreaker associated therewith to open. Immediately after the initiationof the tripping operation and during the opening stroke of the circuitbreaker, collapsible latching means it is reset under the influence ofits spring 25 and thereafter sensitive latch 86 may reset under theinfluence of its spring 82. Since these two members are reset relativelyearly and have considerable time in which to reset, springs 15 and 82may be relatively light. Overcenter type contact St is closed whenarmature 64 is moved upwardly to rotate bell crank 59 whereupon solenoid63 is energized to recharge spring 62 and reset bell crank 59. In viewof the fact that latching means it is collapsible the resetting of bellcrank 59 may take place without disturbing the reset positions ofsensitive latch 89 and the relatively heavy portion of collapsiblelatching means 10 since pawl H is free to move relative to the remainderof collapsible member '10 to a sufiicient extent to allow roller 72 toreassume the position shown in Fig. 3. When the circuit breaker isreclosed, all of the latching means are then reset except latch 41 whichis of relatively small mass and furthermore may be provided with a heavyspring so that the resetting time thereof is negligible and veryhigh-speed reclosing of t e circuit breaker is possible.

In Fig. 4, I have illustrated a modification of the arrangement shown inFig. 3 wherein the electric spring reset means is replaced by amechanical spring reset means. The corresponding parts of Figs. 3 and 4are designated by the same reference numerals. In this arrangement,spring means 62 for supplying the impact tripping force is arranged tobe charged during the opening stroke of the circuit breaker, and, hence,during the upward stroke of rod 42. A pin 85 associated with rod i2 isadapted to strike one end of lever 86 pivotally mounted at 81, the otherend of which is connected to rod ii for compressing spring 62. Theoperation of this arrangement in other respects is identical with thatdisclosed in Fig. 3 and no further explanation will be includedherewith.

In Fig. 5, I have illustrated the sensitive latching means shown inFigs. 3 and 4 as applied to a back pressure type arrangement similar tothat shown in Fig. l, where no spring tripping force is applied, theforce reduction being sufficicnt in this case so that the sensitive tripmay be used. The elements of Fig. 5 which are similar to those of Figs.3 and 4 are characterized by the same reference numerals. In this case,roller 88 which may be similar to roller 23 of Fig. 1 acting against theinclined surface 89 of bell crank 90 pivotally mounted at 9| gives it acounterclockwise bias Which is restrained by the collapsible latchingmember 18 described above having the pawl 'H thereof engaging withroller 62 at the other end of bell crank Si). Resetting of bell crank 90is obtained by means of spring 93. The operation of this arrangementwill also be obvious to those skilled in the art and it is apparentthat, after tripping, the entire system can reset immediately exceptbell crank so and pawl H, the latter being the only part which must besnapped behind roller "i2 at the end of the resettin motion of thecollapsible forcetransmitting structure, not shown.

In the arrangements disclosed particularly in Figs. 3, 4 and 5, thetripping force available from solenoid 83 is so feeble that it isimpossible to use sufficiently heavy springs to reset members 70 and 80in time for rapid reclosing of the circuit breaker. However, bypresetting all the parts which cannot be accelerated by heavy springs asdescribed above, a great deal of time is saved and high-speed reclosingof the circuit breaker is obtained, so as not to disturb the synchronismof an electric distribution system when the tripping of an automaticreclosing circuit breaker is initiated by a fault of very shortduration.

While I have shown and described a particular embodiment of my inventionas applied to an operating mechanism for an electric circuit breaker, itwill be obvious to those skilled in the art that various changes andmodifications can be made without departing from my invention in itsbroader aspects and I, therefore, aim in the appended claims to coverall such changes and modifications as fall within the true spirit andscope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an operating mechanism for a circuit breaker of the trip-freetype, actuating means and means to be actuated, a collapsibleforcetransmitting structure interconnecting the aforesaid means, meansfor latching said force-transmitting structure in the uncollapsedposition when the circuit breaker is closed, means responsive to anabnormal electrical condition for tripping said latching means, saidlatching means comprising a collapsible member including a relativelyheavy portion which resets immediately upon tripping of said circuitbreaker so that said circuit breaker is in condition for immediatehigh-speed reclosing and a relatively light portion which resets at highspeed upon closing of said circuit breaker.

2. In an operating mechanism for a circuit breaker of the trip-freetype, actuating means and means to be actuated, a collapsibleforcetransmitting structure interconnecting the aforesaid means,latching means for holding said force-transmitting structure in theuncollapsed position when the circuit breaker is closed, meansresponsive to an abnormal electrical condition for tripping saidlatching means, said latching means comprising a collapsible memberWhich resets immediately upon tripping of said circuit breaker and whichincludes a relatively heavy portion and a spring biased pawl ofnegligible mass, said pawl being movable relative to said relativelyheavy portion so that said circuit breaker may be relatched in theclosed position without moving the relatively heavy portion of saidlatching means whereby high-speed reclosing of said circuit breaker ispossible.

3. The combination with an operating mcchanism including latching meansfor holding said mechanism in the closed position, of tripping means foractuating said latching means to cause opening of said mechanismcomprising a trip coil sensitive to comparatively small trippingimpulses, said latching means comprising a collapsible member whichresets immediately upon operation of said tripping means including arelatively heavy portion and a relatively light portion, said relativelylight portion being arranged for limited movement with respect to saidrelatively heavy portion so that said operating mechanism may be resetwithout disturbing said relatively heavy portion of said latching means.

4. The combination with an operating mechanism including latching meansfor holding said mechanism in the closed position, of tripping means foractuating said latching means to cause opening of said mechanismcomprising a trip coil sensitive to comparatively small trippingimpulses, said latching means comprising a collapsible member whichresets immediately upon tripping or" said circuit breaker and whichincludes a relatively heavy portion and a springbiased pawl ofnegligible mass movable to a limited extent with respect to saidrelatively heavy portion so that said operating mechanism may be resetwithout disturbing said relatively heavy portion of said latching means.

5. The combination with an operating mechanism including latching meansfor holding said mechanism in closed position, of tripping means foractuating said latching means to cause opening of said mechanismcomprising a trip coil sensitive to comparatively small trippingimpulses, a latch related to said trip coil comprising a collapsiblemember which resets immediately upon deenergization of said trip coil,said latch being so constructed and arranged as to release energy storedin an energy-storage means whereby a releasing blow is delivered to saidlatching means under the influence of said stored energy in response toactuation of said trip coil, and means for storing energy in saidenergy-storage means immediately after the tripping of said operatingmechanism.

6. In an operating mechanism for a circuit breaker of the trip-freetype, actuating means and means to be actuated, a collapsibleforcetransmitting structure interconnecting the aforesaid means,latching means for holding said force-transmitting structure in theuncollapsed position when the circuit breaker is closed, tripping meansfor actuating said latching means to cause opening of said circuitbreaker comprising a trip coil sensitive to comparatively small trippingimpulses, a latch related to said trip coil comprising a collapsiblemember which resets immediately upon deenergization of said trip coiland includes a relatively heavy portion and a portion of negligible massso constructed and arranged that only said portion of negligible mass ismoved when relatching said circuit breaker in the closed position, saidlatch being constructed to release a spring whereby a blow is deliveredto said latching means under influence of the spring energy in responseto actuation of said trip coil, and means for causing restressing ofsaid spring during the opening movement of said circuit breaker so thatsaid mechanism is in condition for immediate reclosing of said circuitbreaker.

CARL THUMIM.

